Torque meter



July 31, 1951 E. A. GALLO ETAL TORQUEMETER 2 Sheets-Sheet 1 Filed Oct. 1, 1949 ATTEIRNEY July 31, 1951v E. A. GALLO ETA}, 2,562,710

TORQUEMETER 2 Sheets-Sheet 2 Filed Oct. 1, 1949 Patented July 31, 1951 TORQUE METER Elia A. Gallo, Englewood, and Willard F. Meyers,

Demarest, N. J., assignors to Wright Aeronautical Corporation, a corporation of New York Application October 1, 1949, Serial No. 119,036

11 Claims. 1

This invention relates to means for measuring torque and is particularly directed to means for measuring the torque output of an engine in which said means is arranged to measure for ward as well as reverse torque and to distinguish between forward and reverse torque.

Aircraft engines are generally provided with torque-meters for measuring their torque output. In addition, automatic power control systems for aircraft engines, particularly of the gas turbine type, generally use the engine torque output as one of the factors controlling engine power. In such an automatic power control system it is desirable that there be a continuous measurement and indication of the engine torque output through zero torque. Accordingly the primary object of this invention comprises the provision of a novel and simple arrangement for measuring the torque output of an engine such that it not only is possible to measure both forward and reverse torque but it is also possible to distinguish between forward and reverse torque. Reverse torque conditions take place when, for example, the aircraft propeller is windmilling and tending to drive the engine.

Other objects of the invention will become apparent upon reading the annexed detailed description in connection with the drawing in which:

Figure l is a schematic view of an engine transmission to which the invention has been applied;

Figure 2 is a diagrammatic development taken along line 2-2 of Figure 1 and illustrating the details of the torque measuring system embodying the invention; and

Figure 3 is a view of the torque measuring gage.

. Referring first to Figure 1 of the drawing, there is illustrated a transmission Ill for an aircraft engine, said transmission comprising an input shaft i2 having a gear 24 formed integral therewith and an output shaft lfi'having a gear l8 splined thereto as indicated at 28. When the transmission IQ is disposed between an aircraft engine and its propeller, the shaft l 2 is connected to said engine and the shaft [6 is connected to said propeller. The gears i l and I8 are concentric and a plurality of circumfer-entiallyspaced pinions 22 are disposed between the gears M and 58 in meshing engagement with said gears. The pinions 22 are journaled'on studs 24 projecting from an annular member 26. Said annular memher is secured against rotation relative to the transmission housing 28 by means schematically indicated; at 3%. whereby the pinions 22 provide a step-down speed ratio drive from the input shaft l2 to the output shaft 16. Since the pinion car== rier member 26 is secured against rotation'to the housing 2t said carrier member constitutes the torque reaction member of the transmission H].

An annular member 32 is secured to the pinion carrier member by screws 34. An oil transfer bushing 36 is disposed between the member 32 and the shaft It for transferring lubricating oil to the pinion bearings 38 from the shaft Iii. cept for details of the means 31) whereby the reaction member 26 is secured against rotation to the transmission housing 28, the transmission It) so far' described is similar to that illustrated in copending application Serial No. 2,383, filed January 15, 1948, by V. Moore, now Patent No. 2,518,708. As will appear, however, the invention is not limited to the specific form of transmission illustrated but is applicable to any transmission having a torque reaction member subjected to a torque proportional to the torque being transmitted.

Referring now to Figure 2, the means 38 for securing the torque reaction member 26 against rotation to the transmission housing 28 comprises a plurality of pairs of pistons symmetrically spaced about the transmission axis and carried by said housing. Three pairs of pistons have been illustrated, a first pair t2 and 42 interconnected by a lever 44, a second pair 46 and 58 interconnected by a lever 56, and a third pair 52 and 5t interconnected by a lever 56. As will appear, how-ever, it is within the scope of the invention to use only one pair or any number of pairs of said pistons. As in the aforementioned copending application, the axes of the-pistons are parallel to the transmission axis. The pistons lil, A2, 46,

48, 52, and 54 are slidable Within cylinders-58, 69,

62, 64, 6t and 68 respectively, said cylinders being formed within the transmission housing 28. Each of the levers 44, 52, and is pivotally mounted midwa of its ends by a pivot pin 'lil carried by the housing 28. The ends of each lever are formed with lateral projections 12 extending into engagement with its adjacent piston. As hereinafter explained liquid under pressure acts against the head of each piston for urging said pistons outwardly into engagement with their respective lever ends 12.

A positive displacement type pump l -l, preferably driven from the shaft 12, is supplied with a liquid, such as engine lubricating oil, through a supply conduit 76. A by-pass passage H3, having a spring loaded pressure relief valve is preferably connected around the pump M to limit its output pressure. Conduits $2, 82, and provide communication between the output side of the pump '54 and an annular groove 88 formed about the piston 40 intermediate its ends. The head end or bottom of the cylinder 53 for the piston 40 constitutes an increased diameter portion 90 and the head end 82 of the piston 40 is movable past the circular edge 84 formed at the junction of the cylinder 58 with-its increased diameter portion 90 to admit liquid under pressure behind the piston 40 from the annular groove 88. From the cylinder head liquid is supplied through --an unrestricted conduit 94 to the heads of the cylinders 62 and 6'0 behind the pistons 46 and 52. The fit of the pistons 45 and52. in their respective cylinders is such that there issomeleakage of oil past these pistons from the piston 40. The pressure of the liquid actingagainst the pistons 40, 45 and is transmitted by a conduit 98 to a suitable gage I86 and/or to a power control-system for the engine.

Oil pressure is supplied behind the pistons 42, 48 and 54 from the pump '14 through a pressure reducing valve M2. The pressure reducing valve I02 is slidably fitted Within a bore I04 in .the transmission housing 28 andsaid valve I02. has an annular groove I06 intermediate its ends. .The valve groove I06 provides communication between the passages 84 and 86. The bottom of the bore I04 is of increased diameter and the head end I08 of the valve It2 is movable past the bore edge I I at the junction of the valve bore I04 with its ;increased diameter portion. A spring I I2 urges the valve 02 toward the bottom of its bore I04 and a nut I i4 closes the opposite end of said bore, said nut being adjustable to vary the compression of the spring H2. A passage H6 provides communication between the bottom of the valve bore i04-and the head end of the cylinderii'ill behind its piston 42. In addition the head ends of the cylinders 64 and (58 are in unrestricted commu- 1;:

nication with the passage i I through apassage H8. Accordingly, the reduced outputpressure 'of the valve 502 acts against all of the pistons 42,

48 and 54 to urge said pistons outwardlyiagainst their respective lever ends I2.

The fit of the pistons 42, 48 and 54 in their cylinders is such that there is a continual leakage flow of oil past said pistons-from the pressure reducing valve I02. With this arrangement, the position of the pressure reducing valve head I08 relative to the metering edge i I0 is such thatrthe pressure at the bottom of the valvebore I04; acting against the valve head :05, always balances the force of the spring! i2 against said valve. Thus, upon an increase inthe output pressure of the pump i i, the oil pressure tends to increase against the valve head 08 but this increase in pressure moves the valve R32 to the left (Figure '2) to further throttle the oil as it flows past the metering edge IIQ until the oil pressure against the valve head 55$ again balances the force of the spring H2. Any adjustment of thonut I I4 varies the compression of the spring I I2 thereby varying the magnitude of the reduced output pressure automatically maintained by the valve I02.

Each lever 44, 50 and-56 has a lateral extension I20 projecting between-a pair of facing shoulders- 22 and I24 on the transmission reaction member 26. Each shoulder I22 and I24 is provided with a concave spherical surface I26 within which a convex spherical button I28 on the associated lever extension 520 fits. With this interconnection or' the reaction member 25 with the pistons through the levers 44, 55 and 56, the fluid is transmitted from the propeller shaft :5 to the engin shaft i2, as when the propeller is wind milling, the torque on the reaction member is reversed from that indicated by the arrow in Figure 2.

Since thepistons 45, 46 and 52 are interconnected by the passage 94, the same fluid pressure necessarily acts against these pistons and this fluidpressure is controlled by the piston 40. The

-pistons42, 48 and 54 are interconnected by the passage IIB so the equal fluid pressures also act against these pistons. This latter iluid pressure,

however, constant and its magnitude is determined by the setting of the pressure reducing valve i02. Because the'fluid pressures acting against the pistons 40, 46 and 52 are equal and because the fluid pressures acting against the pistons 42,48 and 54 are'equaLthe reaction torque on the member is resisted equally by the pairs of pistons whereby said reaction member exerts an equal force againstall of the levers 44. 50 andlfifi and said force is proportional to the torque transmitted by the transmission I9.

If, for example, there is an increase in the forward torque transmitted by the. transmission 80 then there is an increase in the torque proportional force exerted by the reaction member 26 on the lever 44. The lever 44 thereupon rotates counterclockwise to move the head 52 of the piston 46 inwardly further beyond the edge 94 to such an extent that the pressure acting against the piston increases to rebalance the turning forces acting on the lever 44. In this way the piston40 is automatically movable relative to the edge-s4 to vary the magnitude of the fluid pressure acting against said piston in order to maintain the turning forces acting on the lever 44 balanced. 'Since each pair of pistons is subjected .tothe same fluid pressures, When the turning forces on the lever 44 are balanced the corrcsponding forces on the levers are also balanced.

Whenthetorque acting on the transmission reaction member 26 isvzero, the piston 40 assumes a position, relative to its metering edge 94, such that the pressure behind said piston just balances the pressure behind its associated piston 42. At the same time the-pressure behind balance, the piston 40 moves inwardly to increase the opening between its head 92 and the metering edge 94 until the fluid pressure acting against said piston has been increased by an'amount proportional to said torque responsive force thereby again balancing the forces on its lever 44. If, however, the torque increases in the reverse direction from its zero value then the force OI the reaction member 26- on the lever 44 exerts a clockwise turning moment on said lever thereby unbalancing the turning forces on said lever. In response to this unbalance, the piston 40 moves outwardly until the pressure against said piston has been reduced by an amount proportional to said torque thereby again balancing the forces on the lever 44. It follows therefore that; (1) when the torque being transmitted is zero, the fluid pressure acting against the piston 40 is equal to the constant fluid pressure acting against the piston 42; (2) when forward torque is being transmitted, the fluid pressure acting against the piston 40 is greater than the constant fluid pressure acting against the piston 42' by an amount proportional to said forward torque; and (3) when reverse torque is being-transmitted, the fluid pressure acting against the piston 40 is less than the constant fluid pressure acting against the piston 42 by an amount proportional to said reverse torque. Accordingly, the gage I00 is calibrated to read zero torque when the fluid pressure acting on said gage is equal to the output pressure for which the pressure reducing valve I02 is set. Then any increase in the fluid pressure acting on the gage I00,"above the value for zero torque, is a measure of the forward torque on the reaction member and any decrease in the fluid pressure acting on said gage, below this zero torque value is a measure of the reverse torque on the reaction member 26. The gage I00 can therefore be graduated as indicated in Figure 3 so that deflection of its pressure responsive needle I29 to one side of its zero point will indicate and be a measure of forward torque while deflection of said needle to the other side of its zero point will indicate and be a measure of reverse torque. The zero point of the gage I00 can readily be.fixed as follows: When the engine is shut down, so that the torque transmitted is zero, oil is pumped into the system through a normally closed externtal connection I36 communicating with the passage 84, the pressure of said oil being greater than the output pressure for which the reducing valve I02 is set. The position of the gage. needle I29 is then adjusted relative to its scale to read zero. The magnitude of the output pressure of the pressure reducing valve I02 is such that'the turning moment exerted on each lever 44', 50 and 56 by their associated pistons 42, 4B, and 54, respectively, is greater than the turning moment exerted on said lever by the reaction member 26 at maximum reverse torque. Therefore the gage I00 will always respond to a positive fluid pressure from a maximum forward torque through zero torque to maximum reverse torque.

In an actual design, the by-pass pressurerelief valve 80 of the pump I4 was designed to open at a pressure of approximately 425spounds per square inch and the pressure reducing valve I02 was designed to maintain a constant pressure of 68 pounds per square inch on thepistons 42, 48 and 54. These numerical values are merely given by way of example since their actual magnitudes obviously depend on the ranges. of forward and reverse torque acting on the reaction member 26 as well as on the sizes of'the various pistons and on the lengths of the various lever arms. 4

- With the system so far described if the leakage flow path past the pistons 46 and 52 becomes too small, the piston head 92 may notbe able to throttle the leakage flow sufliciently at the metering edge 94 to bring the pressure behind the piston 40 down to the value required to balance the forces acting on the lever 44. If this happens,

- the piston 40 will move outwardly and the lever One or more holes I32 provide communication between said groove and the back side of the piston 40. With this arrangement if, as the piston 40 moves outwardly, it cannot throttle the flow past the metering edge 94 sufliciently to bringthe pressure behind said piston down to'the value required to balance the forces on its lever 44, then'the piston 40 will move outwar'dly only-until its groove I sufficiently vents the backside of the piston 40 beyond the forward edge I34 of the piston bore 58 to balance the V forces on the lever- 44.

modifications.

While we have" described our invention in detail in its present'preferred embodiment, it will be obvious to those skilled in the art, after. understanding our invention, that various changes and modifications may be made therein'without departing from the spirit or scope thereof. We aim in the appended claims to cover all such We claim as our invention: 1. In combination with a transmission including a'member subjected to a torque proportional to the torque transmitted; a piston; a lever interconnecting said piston and member so that upon transmission of torque said member sub- 'jects said lever to a force proportional to the magnitude of said torque, said force urging said lever in a first direction or in a second and opposite rotative direction about the lever pivot axis depending on whether said torque is being transmitted in the forward or in the reverse direction respectively; means for applying a fluid'pressure against said piston for subjecting said lever to a force urging said lever in said second direction vabout its pivot axis; yieldable means for applying ja substantially constant force against said lever for urging said lever in said first direction; and means controlled by movements of said piston for varying said fluid pressure to maintain said forceslbalance'd about the lever pivot axis.

,1 f .2. In combination with'a transmission including a member subjected to a torque proportional to the torque transmitted; a piston; a lever interconnecting said piston and member so that upon transmission of torque said member subjects said. lever to a force proportional to the ma itude of said torque, said force urging said lever in a firstdirectionor in a second and opposite rotative direction about the lever pivot axis dependingpn, whether said torque is being transmitted inthe forward or in the reverse direction f forceurging said lever in said second direction respectively; means for applying a fluid pressure against said piston for subjecting said lever to a about its pivotaxis; yieldable means for applying a substantially constant force against said lever for urging said lever in said first direction:

- ofisaid lever and piston being movable in response valve means controlled by said lever and piston to changesin said torque responsive force; and

.. movements for varying said fluid pressure to maintain- 'said forces "17 .13. .In :combinationzwitlna .transmissioninclud- .ing amember subjected-toa torque proportional .tothe torque transmittedua; pistomzjaa lever interconnecting said piston and .member so that ;upon transmission of .torque;saidmemberrsubjects said. lever .to a force, proportional to the magnitude of said .torque said force-urgingssaid lever inazfirst direction .or. in a second andpppolever for urgingzsaid lever. in said firstxdirection;

:,and valve means :controlled .by; movements of said-.ipiston; for varying .-said :fiuid pressure to .:maintain: saidv forces balanced aboutthe lever pivot. axis.

4. In combination withaatransmission including a member subjected to a torqueproportional to .the torque transmitted; apiston; a lever...in-

terconnecting said piston :and member" so that '-,upon. transmission of torque. said. member; subjects-said lever toa. force proportionaltothe magnitude of said torque, said force urgingsaid lever in a firstzdirection or. in a secondxand opposite rotative direction about the leverupivot-axis depending on whether said torqueisbeing trans- ;rnittedin the forward. or in the. reverse direction respectively; means; for .providing a source. of :fluid under pressure communicating with said piston for urging said piston againstsaid lever;

.to subject said lever to a force. urging said. lever .in'said. second direction; yieldable'means for rapplyingra substantially constant forceagainst ;-said lever for urging said lever in said firstdirection; and :a valve port disposedbetween the .head-of said piston and said source of fluidunder ;pressure, -said piston beingnmovable to open. or

close said valve port to increase or .decrease, re-

- spectively, the. fluid; pressureacting against said piston-to maintain saidforces balanced... about the lever pivot axis.

I5. In combination with atransmission including a member. subjected to a torque. proportional to the torque being transmitted; .a first and second: piston;..a lever interconnecting said pistons and said member. so .that .upontransmission of torque said member subjects said lever to a' force proportional to the magnitude of said torque. and said force urges said lever in afirst or in a second and opposite rotative rdirection about the.lever pivot. axis dependingonwhether said torque is being transmitted inthe forward or in the reverse direction. respectively; means for' applying a constant fluid pressureagainst said"first,piston for subjecting said lever to a constant force. urging said lever in said first direction about its pivot axis; means for applying a fluid pressure against said second piston for subjecting said lever to a force urging said lever in. said second direction about its pivot axis; and means controlled by movements of said. piston for varying saidfluid pressure to maintain said forces balanced about the lever pivotaxis.

6. In the combination recited in'claim5'in which the means'for applying a constantfiuid pressure includes a pressure reducing valve.

7 '7. In combination with a transmission including a member subjected to a torqueproportional to the torque being transmitted; a; first and a'second piston; a lever interconnecting said pistons 5.8 andrsaid member so; that .upon transmission. of torque-said. member subjects said lever. to a force uproportionalto themagnitude of saidtorqueand ;-.said forceurges said lever ina first orina second -..and. .oppositep-rotative 1 direction about the lever ,pivot.axisrdepending on whethersaid torque is beingtransmitted'in the forward or in the reverse :xdirectionsrespectively; means providing a. source .offluid under pressure communicating withsaid .pistons iorurgingsaidpistons against said lever, the pressure "of said fluidacting against said first .piston'subjectingrsaid lever toa force urging said levelin. said: first direction and the pressure of said fluid acting against saidsecond pistonsub- 15.;jecting.said .leverto a force. urging .said leverin said second; direction a pressure reducing valve ifor-automaticallymaintaining a constant reduced pressureofsaid fluid onsa-id first piston; and a valve; port varied.bymovementsof said second piston for varying the pressure of said fiuidacting 'zagainstsaid second .piston so as to maintain said forces balanced about the lever pivot axis.

8rln combinationwith a transmission includ- -..ing:a;memb.er. subjected to a torque proportional :.t0i1'rh torquezbeing transmitted; a first and a sec- -ond;piston;-..a lever interconnecting said pistons randjsaidrmemberso.that upon transmission of torquasaidanember subjectssaid lever to a force :proportionalwto the. magnitude of said torque and s05.saidiforceurges said lever in afirst. or in asecond .andsopposite; rotative direction about the lever :pivot: axis depending: on-whether said torque .is cbeing transmitted in the forward orin the reverse :di-rection; respectively; means providing: a 'source 1 ofIluidunder pressure communicating with said :pistons .for urging said pistons against/said lever, 'theipressure' of saidxfiuid acting against said first :rpiston subjecting-said lever to. a force urging said .lever; int'saidffir'st direction and .the pressure of :4oasaid tfiuidLactingagainst. said second pistonsub- "jectingisaid lever to a force .urging said leverin "saidsecondidirection pressure' reducing valve for automatically maintaining a-constant reduced "pressure-of said? fluid on said first piston; and a '-'-l5"Va1Ve port disposd between the" head of said sec- *ond"piston andsaid source of fluid, said second pistonxbeingnnovable to open or close said port .i'to'zincrease or :decrease, respectively, the fluid pressure actingagainstsaidsecond piston so as .to-rnaintain said forces balanced about the lever :pivot axis.

'.9.'rIn'.thecombination recited in claim 8 and iincluding:means'adapted to vent the fluid pressure acting: against said second piston in the event saidi fluid-.pressurecannot bereduced sufficiently 0- second'piston'to relieve the fluid pressure-acting i 70:01 'said leversinterconnectingsaid member and "pistons so that upon transmissionof torque'said member subjects-said lever to a force proportional to the magnitude" of said torque and said force urges said lever'in'atfirst' or .in a second and opposite rotative'direction' about the lever pivot axis depending on Whether said torque is being transmitted in the forward or in the reverse direction respectively; a source of fluid under pressure communicating with said pistons for urging said pistons against their respective levers, the pressure of said fluid acting against the first piston of each pair of pistons subjecting the associated lever of said first piston to a force urging said lever in said first direction and the pressure of said fluid acting against the second piston of each of said pair of pistons subjecting the associated lever of said first piston to a force urging said. lever in said second direction; a pressure reducing valve for automatically maintaining a constant reduced pressure of said fluid against said first pistons; and valve means controlled by movements of at least one of said second pistons for varying the 10 pressure of said fluid acting against said second pistons so as to maintain the forces acting on each said lever balanced about the lever pivot axis.

" ELIA A. GALLO.

WILLARD F. MEYEBS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 924,242 Kenerson June 8, 1909 2,019,755 Zerbe et a1 Nov. 5, 1935 2,289,285 Chilton July 7, 1942 2,493,012 Moore et al Jan. 3, 1950 

